Human infection with cytomegalovirus (HCMV) has always been commonplace; however, only recently, with the development of organ transplantation and its attendant immunosuppression, has HCMV-associated disease become an important cause of morbidity and mortality in the clinical setting. With this increase in the incidence of HCMV disease, it has become recognized that animal models need to be developed that provide 1) insight into the pathogenesis of the infectious process and 2) preclinical evaluation of novel therapeutic agents. As a first step towards generating an animal model, we have developed a sensitive Western blot assay to screen for CMV seroconversion in rhesus macaques. Additionally, we have cloned and sequenced the rhesus CMV DNA polymerase and phosphotransferase genes. Both genes exhibit a high degree of amino acid sequence similarity with the corresponding HCMV genes and display the same particular amino acids which sensitize HCMV to the antiviral drug ganciclovir. We believe the progress we have made will enable us to establish the rhesus macaque as an excellent animal model to identify and evaluate novel antiviral therapeutic agents.